Galvanometers, basically, have their moving coils or moving systems secured in the instrument in two different ways. The general construction of the galvanometer need not be described since galvanometers of various types have been known for many decades. All mechanical constructions require a compromise between mechanical strength, and sturdiness on the one hand, and sensitivity of the instrument on the other. Thus, galvanometer coils operating in an magnetic field which are subject to shock or vibration, and thus must be reliably and sturdily mounted, usually have the moving system journaled in bearings. These bearings may be artificial jewels, the moving systems being provided with pointed pins which are journaled in the jewels, similar to watch movements. Current is supplied to the galvanometer coil by spiral springs. This arrangement, while providing good and reliable bearings for the movable system has the disadvantage that frictional forces are introduced which lower the sensitivity and accuracy of the instrument.
Instruments which meet the highest requirements regarding sensitivity have been proposed in which the movable galvanometer coil is suspended on a stretched metal ribbon. Such ribbon suspensions provide for a floating attachment of the galvanometer coil to a frame. The ribbons themselves provide the current supply to the frame. Upon deflection of the galvanometer coil, that is, when a current is passed through the coil which is placed in a magnetic field, the ribbons will twist and, due to the elasticity of the metal ribbons, will also provide the necessary reset torque. Such systems, while being sensitive, have the disadvantage that they are subject to shock or vibration. To provide even a reasonable degree of strength and sturdiness to such instruments, it is necessary that the stretching ribbons which hold the galvanometer frame have a certain thickness and width. Thus, the suspension ribbons cannot be made as thin as would be desirable and thus the reset torque cannot be decreased to the extent necessary merely to move the galvanometer coil and an associated indicating device. The sensitivity of the instrument thus is limited by the elasticity of the suspending ribbons which, due to the requirements of suitable mechanical strength, have a lower limit which cannot be passed.